BIRTH DEFECTS EPIDEMIOLOGY AND SURVEILLANCE Peter Langlois, PhD, Senior Scientist Birth Defects Epidemiology and Surveillance Branch Texas Department of State Health Services
BIRTH DEFECTS EPIDEMIOLOGY AND
SURVEILLANCE
Peter Langlois, PhD, Senior Scientist
Birth Defects Epidemiology and Surveillance Branch
Texas Department of State Health Services
Outline
• Texas birth defects registry
– Overview
– Describing the occurrence of birth defects
– Cluster investigations
• Some research on causes of birth defects
• Zika virus and microcephaly
Texas Birth Defects Registry:Overview
History
1991 Headlines
The Texas Birth Defects Registry: What It Is
• One of the largest active birth defects surveillance systems – Passive vs. active surveillance
• Extensive quality control checks– Includes review of roughly 50% of records by
clinical geneticists
• Computerized database of infants and pregnancies affected by birth defects
The Texas Birth Defects Registry: Case Definition
• Infant/fetus has structural or chromosomal anomaly
• Mother resident in TX at delivery
• Birth defect diagnosed prenatally or within first year of life
• Includes all pregnancy outcomes
The Texas Birth Defects Registry: What It Does With The Data
• Describe occurrence of birth defects in Texas
• Conduct cluster investigations
• Work with others in:– Research
– Prevention
– Linking families to available services
Texas Birth Defects Registry:
Describing the Occurrence of BDs by Time, Place, and Person
Birth Prevalence of Children With Any Monitored Birth Defect by Year
0
100
200
300
400
500
600
700
1999 2001 2003 2005 2007 2009 2011 2013
Cases p
er
10000 l
ive b
irth
s
Birth Year
The Increase May Be Due Largely to Better Detection/Ascertainment Over Time
Average Annual % Change
Birth Defect Category All Cases Isolated Cases
Least Susceptible to Diagnostic Variability
e.g. gastroschisis, limb reduction defects
- 0.2 - 3.8
Somewhat Susceptible
e.g. hypospadias, trisomy 21
+ 0.5 - 2.7
Mid Susceptibility
e.g. anotia/microtia, tetralogy of Fallot
+ 1.4 - 0.4
Quite Susceptible
e.g. VSD, renal agenesis/dysgenesis
+ 0.8 + 3.1
Most Susceptible to Diagnostic Variability
e.g. ASD, cataract
+ 2.0 + 2.9
Birth Prevalence of Children With Gastroschisisby Year
0
1
2
3
4
5
6
7
1999 2001 2003 2005 2007 2009 2011 2013
Cases p
er
10000 l
ive b
irth
s
Birth Year
Ambient Levels of Benzene and Spina Bifida, Texas 1999-2004
Benzene Level (ug/m3) Adj Odds Ratio (95% CI)
0.12 – 0.45 1.00 (referent)
>0.45 – 0.98 1.77 (1.04 - 3.00)
>0.98 – 1.52 1.90 (1.11 – 3.24)
>1.52 – 2.86 1.40 (0.82 – 2.38)
>2.86 – 7.44 2.30 (1.22 – 4.33)
Lupo PJ et al. 2011 Environmental Health Perspectives
Proximity of Children with Birth Defects to Pediatric Genetics Clinics, Texas, 1999-2003
Represents 22,875 cases from the Texas
Birth Defects Registry delivered 1999-2003
Case AP et al. Birth Defects Research Part A 82.11 (2008)
Prevalence of Down Syndrome (Trisomy21), by Maternal Age, Texas, 1999-2007
0
20
40
60
80
100
120
140
<20 20-24 25-29 30-34 35-39 40+
Ca
ses
per
10
,00
0 L
ive
Bir
ths
Mother’s Age
For your own queries:http://healthdata.dshs.texas.gov/Registries/BirthDefects
Texas Birth Defects Registry:
Cluster Investigations
Birth defect cluster
One definition: more than the expected number of cases of a birth defect in a population group for a defined geographic area and a defined time period
What causes birth defect clusters?
• Chance…normal fluctuation over time in the occurrence of birth defects
• Changes in diagnostic practices or hospital referral patterns
• Shared exposure the cases have in common
Why investigate birth defect clusters?
• Generate new clues about causes of birth defects (RARELY)
• Respond to the concerns of community members
• Educate/inform the public about birth defects
A Recent Cluster Investigation: Trisomy 18
In the Bryan/College Station Area
Cluster of 4 babies conceived during August 2009–February 2010 to residents of Brazos County 2 families from Bryan
2 families from College Station
Concern about possible relationship to chemical plant fire on July 30, 2009
Trisomy 18 by Estimated Date of Conception
0
1
2
3
19
98
Jan
19
98
Ju
l
19
99
Jan
19
99
Ju
l
20
00
Jan
20
00
Ju
l
20
01
Jan
20
01
Ju
l
20
02
Jan
20
02
Ju
l
20
03
Jan
20
03
Ju
l
20
04
Jan
20
04
Ju
l
20
05
Jan
20
05
Ju
l
20
06
Jan
20
06
Ju
l
20
07
Jan
20
07
Ju
l
20
08
Jan
20
08
Ju
l
20
09
Jan
20
09
Ju
l
20
10
Jan
20
10
Ju
l
Cas
es
Brazos County
0
1
2
3
19
98
Jan
19
98
Ju
l
19
99
Jan
19
99
Ju
l
20
00
Jan
20
00
Ju
l
20
01
Jan
20
01
Ju
l
20
02
Jan
20
02
Ju
l
20
03
Jan
20
03
Ju
l
20
04
Jan
20
04
Ju
l
20
05
Jan
20
05
Ju
l
20
06
Jan
20
06
Ju
l
20
07
Jan
20
07
Ju
l
20
08
Jan
20
08
Ju
l
20
09
Jan
20
09
Ju
l
20
10
Jan
20
10
Ju
l
Cas
es
Surrounding Counties
Fire, 7/30/2009
Some Research on Causes of Birth Defects
Texas Center for Birth Defects Research
and Prevention, 1996-2013
Cooperative agreement grant with CDC
One of 10 centers in the nation
National Birth Defects Prevention Study
Largest population-based case-control study on birth defects to date
Study includes 30 specific birth defects
Additional clinical review and classification of cases
Computer-assisted maternal phone interview
Cheek cell samples (DNA): mom, dad, infant
Pre-pregnancy Obesity and Selected
Isolated Birth Defects, 1997 – 2002
0
1
2
3
AN SB HYD A/M CP CLP Ano HYP LIM HEA OMP GAS
Waller DK et al. 2007. Archives Pediatr & Adolesc Med
aOR
Fever, Antipyretics, and Oral Clefts,
1997-2004: Adjusted Odds Ratios
_I: Isolated defects; _M: Multiple defects
Hashmi S. 2010. Birth Defects Research Part A
Zika Virus and Microcephaly
Current Zika Virus Outbreak
• Fall 2015: NE Brazil reported a twenty-fold microcephaly increase that coincided with local transmission of Zika virus
• February 2016: World Health Organization declares Zika to be a global Emergency
• August 2016: First cases of Zika virus infection locally spread by mosquitos in continental US
Reported occurrence of Aedes aegypti & albopictus
by county in the United States
Maps showing the reported occurrence of Ae.
aegypti (A) and of Ae. Albopictus (B) by
county between 1 January 1995 and March
2016 in the United States.
Micah B. Hahn et al. J Med Entomol
2016;jme.tjw072
A B
Definition
•Clinical finding of a small head (when compared with infants of the same sex and age).
•CONGENITAL MICROCEPHALY: present prenatally or at birth/delivery.
Head Circumference
• Used to measure “severity”
• Severe: < 3rd percentile for age and sex
• Also called occipital-frontal circumference (OFC)
Some Challenges for Public Health Surveillance
• Some clinicians use different cut-points
– < 5th percentile, < 10th percentile
– Based on standard deviations below average
– Subjective assessment
• HC measurement sometimes missing
• Cause in many cases can be explained
– Can be a feature of other birth defects
– Several known causes (in utero infections, maternal conditions, teratogens)
Microcephaly Cases in Texas2008-2012
CATEGORY CASES% OF
TOTAL CASES
BIRTH PREVALENCE (CASES/10,000 LIVE
BIRTHS)Explained Cases 856 30% 4.4
Unexplained Cases 2,013 -- 10.3
Unexplained Severe Cases 615 21% 3.2
Unexplained Less Severe Cases 1,398 49% 7.2
Total Cases 2,869 100% 14.7
0.00
2.00
4.00
6.00
8.00
10.00
12.00
14.00
16.00
18.00
20.00
19
99
20
00
20
01
20
02
20
03
20
04
20
05
20
06
20
07
20
08
20
09
20
10
20
11
20
12
Pre
vale
nce
(C
ase
s/1
0,0
00
Liv
e B
irth
s)
Delivery Year
Microcephaly by Year and Subgroup TX 1999-2012
Total Cases
Unexplained Cases
Severe Microcephaly (<3 Percentile)
MICROCEPHALY AND WHAT ELSE?
BIRTH DEFECT # CASES/YR
MICROCEPHALY (causal association) 819
OTHER BRAIN AND SKULL ANOMALIESAbnormal brain cortex, corpus callosumFetal brain disruption sequence
2438
NEURAL TUBE DEFECTS + HOLOPROSENCEPHALYAnencephaly, spina bifida, encephaloceleHoloprosencephaly
337
OTHERSEye abnormalitiesCongenital contractures (e.g. arthrogryposis)Congenital deafness
591
TOTAL 3550
Thanks
For more information:
Peter Langlois, PhD
Phone: 512-776-6183